[Relationship between chloride tolerance and polyamine accumulation in Glycine max, Glycine soja, and their hybrid seedlings].

The seedlings of the F4 hybrid strain 'JB185' selected for salt tolerance generation by generation, their parents Glycine max cv. Jackson and Glycine soja population 'BB52' were treated with different NaCl concentrations and iso-osmotic (-0.53 MPa) PEG-6000, NaCl, Na+ (without Cl-) and Cl- (without Na+) solutions for 6 d. The results showed that: (1) The relative electrolyte leakage and malondialdehyde (MDA) content in leaves of the above three soybean seedlings showed an increase trend when the NaCl concentration was elevated, but chlorophyll contents decreased except the significant increase in 'BB52' and 'JB185' under NaCl 50 mmol/L stress. The change in 'JB185' was between its parents. (2) Under different iso-osmotic stresses, the relative electrolyte leakage and MDA contents in leaves of three soybean seedlings also increased mostly, the changes in 'BB52' and 'JB185' under Na+ (without Cl-) stress were more than those under Cl- (without Na+) stress. The free and bound Put, Spd and Spm contents in leaves all increased when compared with the control, the ratios of free (Spd+Spm)/Put and total bound polyamines in 'BB52' and 'JB185' seedlings under Na+ (without Cl-) treatment were the lowest one among three iso-osmotic salt stresses. The results indicate that the F4 hybrid strain 'JB185' is more sensitive to Na+ than Cl- as its wild parent 'BB52' population.

Silicate improves growth and ion absorption and distribution in aloe vera under salt stress.

Si 2.0 mmol/L in irrigation solution alleviated significantly the inhibition of NaCl stress of 100 or 200 mmol/L to aloe growth. Exogenously applied Si decreased significantly Na(+) and Cl(-) contents, increased K(+) content and K(+)/Na(+) ratio and selectivity ratio of absorption (AS(K, Na)) and of translocation (TS(K, Na)) to K(+) and Na(+) in aloe plant under both NaCl 100 and 200 mmol/L stresses for 30 d. In this way, the ion homeostasis in aloe plant under NaCl stress was maintained, as was proved by X-ray microanalysis of root tip and leaf across sections. One of the mechanisms to achieve this may be the significant enhancement of H(+)-ATPase activities by the addition of silicate in plasma membrane and tonoplast, H(+)-pyrophosphatase (H(+)-PPase) activity in tonoplast isolated from aloe root tips under NaCl stress.

[The relations between polyamine types and forms and polyamine oxidase activities in barley seedlings under salt stress].

The three polyamines (Put, Spd and Spm) and their different forms (free, perchioric acid soluble and insoluble conjugated) together with polyamine oxidase (PAO) activities were measured in barley (Hordeum vulgare L. KP7) seedlings under salt stress. The results showed that the free polyamines were dominant forms among three polyamines, account about 2/3 total polyamines. All three polyamines decreased in roots and leaves after 8 d under NaCl 200 mmol/L stress. The free polyamine content decreased dramatically as well as soluble conjugated polyamine content, while the insoluble ones changed little. Different concentration salt stress increased markedly the ratios of (Spd+Spm)/Put and decreased significantly the total polyamine content in roots and leaves. PAO activities in roots was increased at first and then decreased under NaCl stress, while in leaves the activities changed in opposite direction. It has been noted that the sum of free Spd and Spm (Spd+Spm) content is reversely correlated with PAO activity changes, which suggests that PAO might regulate the free polyamine content, therefore, the contents of the soluble and insoluble conjugated polyamines were affected.

Tonoplast H+-ATPase activity in barley roots is regulated by ATP and pyrophosphate contents under NaCl stress.

The changes in ATP and PPi contents in roots under NaCl stress, and the effect of PPi on tonoplast H(+)-ATPase activity were studied with two barley cultivars differing in salt tolerance. The results showed that tonoplast H(+)-ATPase activity in salt-tolerant barley cultivar "Tanyin 2" roots increased obviously under NaCl 200 mmol/L (containing half-strength Hoagland solution) for 2 d, and decreased gradually. Tonoplast H(+)-PPase activity always decreased under NaCl stress. For salt-sensitive barley cultivar "Kepin 7", both tonoplast H(+)-ATPase and H(+)-PPase activities decreased during NaCl stress, as compared with control(grown in half-strength Hoagland solution), ATP content of "Tanyin 2" roots increased under NaCl stress for 2 d, and decreased on 4 d after NaCl stress, as compared with control. In "Kepin 7" roots, ATP accumulation was inhibited during NaCl stress. Pyrophosphate (PPi) content increased slightly both in "Tanyin 2" and "Kepin 7" roots under NaCl stress. Tonoplast H(+)-ATPase activity was inhibited competitively by PPi. These results indicated that the increase in rate of ATP accumulation might be essential for the stimulation of tonoplast H(+)-ATPase activity induced by NaCl. The decrease in ATP content and the inhibition of PPi might result in the decrease of tonoplast H(+)-ATPase activity in barley roots under NaCl stress.

Relationship between AtPase activity and conjugated polyamines in mitochondrial membrane from wheat seedling roots under osmotic stress.

The effects of osmotic stress on the ATPase activity, the contents of -SH group and conjugated polyamines in mitochondrial membrane from wheat seedling [Triticum aestivum L. cv. Yumai No. 18 (drought-tolerant) and cv. Yumai No. 9 (drought-sensitive)] roots were investigated. The results showed that ATPase activity and -SH group content decreased with polyethylene glycol(PEG) 6000(-0.55 MPa) treatment for 7 d, in concert with the decrease of the ratio of noncovalently conjugated spermidine (NCC-Spd)/noncovalently conjugated putrescine(NCC-Put) and increase of the covalently conjugated putrescine (CC-Put). Osmotic stress injury to Yangmai No.9 seedlings was alleviated greatly with 1 mmol/L exogenous spermidine(Spd), in concert with marked increases of the ratio of NCC-Spd/NCC-Put, -SH group contents and ATPase activity in mitochondrial membrane. Under osmotic stress, the concomitant treatment of Yumai No. 18 seedlings with methylglyoxyl bis(guanylhydrazone) (MGBG), an inhibitor of S-adenosyl methionine decarboxylase(SAMDC), and phenanthrolin (o-Phen), an inhibitor of transglutaminase(TGase), caused a significant decrease of the ratio of NCC-Spd/NCC-Put, CC-Put contents, respectively, in concert with the marked decreases of ATPase activity, -SH group content and its tolerance to osmotic stress. All the results above suggested that osmotic stress tolerance of wheat seedlings was associated with the ATPase activity, the contents of -SH group, NCC-Spd and CC-Put in mitochondrial membrane.

[Nitric oxide alleviates growth inhibition of maize seedlings under NaCl stress].

The effect of nitric oxide (NO) on growth of maize seedlings under 100 mmol/L NaCl stress was studied. The results showed that 0.1-200 mumol/L sodium nitroprusside (SNP), especially 100 mumol/L SNP, increased dry accumulation in maize seedlings significantly, the chlorophyll content, K(+)/Na(+) ratio and (Spd+Spm)/Put ratio, and decreased electrolyte leakage. These results suggest that NO may alleviate the damage caused by NaCl stress through increasing K(+) uptake and transport to shoots and decreasing Na(+) uptake and transport, and also through enhancing the conversing of Put to Spd and Spm.

[Salt-tolerance evaluation of seedlings of medicinal Chrysanthemum morifolium cultivar].

OBJECTIVE: To evaluate salt tolerance of seedlings of 4 medicinal C. morifolium cultivars to be transplanted, and to expand the planting area. METHOD: Seedlings were cultivated in hoagland nutrient solution containing various concentrations of NaCl for 30 days. The height, dry weight and chlorophyll content were investigated. Identification index mainly in relative growth rate, the evaluation of NaCl effects on the growth, K+, Na+ and Cl- distribution in seedlings were surveyed. RESULT AND CONCLUSION: The salt tolerance was difference among four cultivars of C. morifolium. The salt tolerance of "Dabaiju" and "Changbanju" was weak, while "Hongxinju" and "Xiaobaiju" was strong. "Hongxinju" and "Xiaobaiju" may be planted in salinte soil area.